This invention relates to the general field of separating fluids by means of their different permeation rates through a semi-permeable membrane. More specifically, the invention involves a new and improved, inexpensive, easily operable and compact separation apparatus of high dialysis efficiency for use in simultaneous dialysis and ultrafiltration by exactly controlling the amount of ultrafiltration rate.
Methods and apparatuses for fluid separation and concentration by the principle of dialysis and ultrafiltration through a semi-permeable membrane have been generally known. For example, these techniques have been heretofore used for separating or concentrating bacteria, protein, or colloidal substances in the manufacture of medicines or foods, and the hemodialysis procedure is a practical treatment in the medical field.
In many practical cases improvement of dialysis efficiency and exact control of a ultrafiltration rate are desired. Particularly, in the case of hemodialysis, when removing waste components and water from blood by dialysis and ultrafiltration, insufficient removal of waste components or inexact control of ultrafiltration rate may result in serious consequences to the patient. Excessive water removal may cause reduction of blood pressure or death from shock.
Although improvements in the efficiency of dialysis or exact control of the ultrafiltration rate are extremely important, conventional devices which have high dialysis efficiency are bound to have inaccurate ultrafiltration control. On the other hand, conventional devices with exact ultrafiltration control are found to have low dialysis efficiency.